MIAMI , Florida -LRB- CNN -RRB- -- Described as `` an extremely dangerous Category 4 hurricane , '' Hurricane Bill was churning closer to the Atlantic island of Bermuda on Wednesday , forecasters said .

Most forecast maps show Hurricane Bill passing to the west of Bermuda .

Although Bill is not expected to make a direct hit on the island , forecasters cautioned that the storm is large and will generate large swells on Bermuda as well as the islands of the northeast Caribbean Sea over the next day or two .

Swells may also affect the eastern United States on Friday and Saturday , the National Hurricane Center said . CNN meteorologists said Bill could cause cause dangerous rip tides and some coastal flooding in the northeast United States and could move very close to or make landfall in Newfoundland , Canada , early next week .

In addition , Bill may strengthen further over the next couple of days , forecasters said .

As of 5 p.m. ET , Bill 's center was about 335 miles northeast of the Leeward Islands and about 970 miles south-southeast of Bermuda , the hurricane center said .

`` It 's a little too early to evaluate what kind of direct impact Bill may have , '' said Jack Bevin , a senior hurricane specialist . `` Most of the computer guidance has the storm passing between Bermuda and the U.S. coastline , then turning northeastward . ''

Other models show Bill turning more sharply out to sea and not affecting any areas , he said .

Bill 's maximum sustained winds were at 135 mph Wednesday afternoon . It was moving northwest at near 20 mph and was expected to continue that motion over the next day or so , turning north-northwest by late Friday .

Five-day forecast maps show Bill passing to the west of Bermuda before turning to the northwest .

`` Bill is a large tropical cyclone , '' the National Hurricane Center said . Hurricane-force winds extended up to 85 miles from its center , with tropical storm-force winds extending up to 230 miles out .

CNN Radio 's Andrew Spencer and Lee Garen contributed to this report .

@highlight

Storm is not expected to make a direct hit on Bermuda

@highlight

But island , eastern United States could see large swells

@highlight

Category 4 hurricane 's maximum sustained winds are at 135 mph